Facebook says this is just a method to reduce incoming spam for Facebook users with large subscriber counts and big online presences. If you haven’t been able to replicate it yet, that’s because Facebook — as it typically does with new features — is only testing it with a small number of users.

“We are testing some extreme price points to see what works to filter spam,” a Facebook spokesperson told The Wall Street Journal in response to queries about the new pricing scheme.

It’s also intended that users can only send one of these kinds of messages per week. For a normal user, $1 might seem like a lot to send a message to a friend, but for a fan to ensure that someone like Justin Bieber receives a message, it might not be that much.

Today we’re starting a small experiment to test the usefulness of economic signals to determine relevance. This test will give a small number of people the option to pay to have a message routed to the Inbox rather than the Other folder of a recipient that they are not connected with.

Several commentators and researchers have noted that imposing a financial cost on the sender may be the most effective way to discourage unwanted messages and facilitate delivery of messages that are relevant and useful.

It does raise questions as to how much a message to Zuck might be worth — for example, if a startup is looking for funding and wants to reach out to a prominent venture capitalist on Facebook, it could use a service like this to do business.

But for the time being, Facebook’s actual reasoning is decidedly less sinister.